Pathways of Decomposition of Indole Derivatives 



191 



and of the hydrazones of the DNPH reaction in the case of IPA has, 

 on a few occasions, fmnished additional evidence of the acidic or neu- 

 tral nature of some of the products of decomposition. 



Tautomerization and Polymerization 



The presence of two tautomers in chromatograms of IPA was 

 demonstrated (26, 27, 29). It is possible that the presence of two forms 

 of lA with different Rf values evidenced by the wavy pattern in 



■ •.■.■.■.■.■.'i\'A\\.^ 1 



RED ESgREEN E2] yellow m ^^^e'aS i^ ^S'S 



COLOR 



Fig. 7. Double chromatogiam of ultraviolet decomposition products of indole-3- 

 acetic acid. Ascending chromatography. Acetone and water 8:2 in both directions, 

 in an atmosphere saturated with vapors of acetic acid. A, distribution of spots after 

 the first nm. B, after the second run. The solution was applied at the origin in 

 the small circle (I) and the sheet was left overnight for equilibration in the chro- 

 matographic tank. This resulted in diffusion up to the limit of the greater circle at 

 the origin. The spots bet\\'een I and II and between III and IV seldom appeared in 

 other chromatograms and were not numbered. The diagonal of the chromatogram 

 in B is indicated as an interrupted line. The center of primary spots (substances 

 present in the solution) is indicated as large dots, that of secondary spots (formed 

 during chromatography from the substances whose primary spot is on the same 

 horizontal line) as small dots. The isolated spot on the diagonal, in between the 

 tails of spot V and IX is from a substance presumably present in the solution but 

 entirely decomposed during the second chromatography. The secondary spots of IV, 

 V and IX at the same horizontal level presumably originated from this substance. 

 Fluorescence colors, ultraviolet absorption, and visible color indicated by con- 

 ventional hatching. Heavier hatching indicates stronger intensity of fluorescence. 



